An electron spin resonance study of the reactions of alkoxyl and trimethylsiloxyl radicals with dialkyl sulphoxides

Abstract

Qualitative and quantitative studies have been made of the dealkylation of dialkyl sulphoxides by t-butoxyl and trimethylsiloxyl radicals. Dimethyl sulphoxide undergoes S_H2 reaction at sulphur much less readily with Bu^tO˙ than with HO· or Me₃SiO·. The rate of t-butoxydealkylation of symmetrical and of mixed dialkyl sulphoxides increases with the stability of the displaced alkyl radical, providing steric effects are not dominant. Siloxydealkylation of sulphoxides appears to be more rapid and less selective than t-butoxydealkylation. and it is suggested that the electrophilicity of the attacking oxyl radical is an important factor in determining rate and selectivity. The cyclic sulphoxides [graphic omitted]O(n= 2–4) undergo increasingly rapid ring opening as n decreases, a trend attributed to relief of angle strain.

No e.s.r. spectra of suiphuranyloxyl radicals. R₂S(O)OX or R(RO)S(O)OX, were detected during the reactions of XO· with sulphoxides or with alkyl alkanesulphinates, respectively.